Grade: N35,N38,N40,N42,N45,N48,N50; N35M,N38M,N40M,N42M,N45M,N48M; N33H,N35H,N38H,N40H,N42H,N45H; N30SH,N33SH,N35SH,N38SH,N40SH,N42SH; N28UH,N30UH,N33UH,N35UH,N38UH,N40UH; N28EH,N30EH,N33EH,N35EH; N28AH,N30AH,N33AH,N35AH; Shape and size: block, disk, ring, rod, arch, tile, etc., Various sizes and shapes can be made depending upon user's requirements.